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-rw-r--r--include/linux/rcupdate.h46
1 files changed, 10 insertions, 36 deletions
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 5a75d19aa661..6a94cc8b1ca0 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -44,7 +44,6 @@
44#include <linux/debugobjects.h> 44#include <linux/debugobjects.h>
45#include <linux/bug.h> 45#include <linux/bug.h>
46#include <linux/compiler.h> 46#include <linux/compiler.h>
47#include <linux/percpu.h>
48#include <asm/barrier.h> 47#include <asm/barrier.h>
49 48
50extern int rcu_expedited; /* for sysctl */ 49extern int rcu_expedited; /* for sysctl */
@@ -300,41 +299,6 @@ bool __rcu_is_watching(void);
300#endif /* #if defined(CONFIG_DEBUG_LOCK_ALLOC) || defined(CONFIG_RCU_TRACE) || defined(CONFIG_SMP) */ 299#endif /* #if defined(CONFIG_DEBUG_LOCK_ALLOC) || defined(CONFIG_RCU_TRACE) || defined(CONFIG_SMP) */
301 300
302/* 301/*
303 * Hooks for cond_resched() and friends to avoid RCU CPU stall warnings.
304 */
305
306#define RCU_COND_RESCHED_LIM 256 /* ms vs. 100s of ms. */
307DECLARE_PER_CPU(int, rcu_cond_resched_count);
308void rcu_resched(void);
309
310/*
311 * Is it time to report RCU quiescent states?
312 *
313 * Note unsynchronized access to rcu_cond_resched_count. Yes, we might
314 * increment some random CPU's count, and possibly also load the result from
315 * yet another CPU's count. We might even clobber some other CPU's attempt
316 * to zero its counter. This is all OK because the goal is not precision,
317 * but rather reasonable amortization of rcu_note_context_switch() overhead
318 * and extremely high probability of avoiding RCU CPU stall warnings.
319 * Note that this function has to be preempted in just the wrong place,
320 * many thousands of times in a row, for anything bad to happen.
321 */
322static inline bool rcu_should_resched(void)
323{
324 return raw_cpu_inc_return(rcu_cond_resched_count) >=
325 RCU_COND_RESCHED_LIM;
326}
327
328/*
329 * Report quiscent states to RCU if it is time to do so.
330 */
331static inline void rcu_cond_resched(void)
332{
333 if (unlikely(rcu_should_resched()))
334 rcu_resched();
335}
336
337/*
338 * Infrastructure to implement the synchronize_() primitives in 302 * Infrastructure to implement the synchronize_() primitives in
339 * TREE_RCU and rcu_barrier_() primitives in TINY_RCU. 303 * TREE_RCU and rcu_barrier_() primitives in TINY_RCU.
340 */ 304 */
@@ -358,9 +322,19 @@ void wait_rcu_gp(call_rcu_func_t crf);
358 * initialization. 322 * initialization.
359 */ 323 */
360#ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD 324#ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
325void init_rcu_head(struct rcu_head *head);
326void destroy_rcu_head(struct rcu_head *head);
361void init_rcu_head_on_stack(struct rcu_head *head); 327void init_rcu_head_on_stack(struct rcu_head *head);
362void destroy_rcu_head_on_stack(struct rcu_head *head); 328void destroy_rcu_head_on_stack(struct rcu_head *head);
363#else /* !CONFIG_DEBUG_OBJECTS_RCU_HEAD */ 329#else /* !CONFIG_DEBUG_OBJECTS_RCU_HEAD */
330static inline void init_rcu_head(struct rcu_head *head)
331{
332}
333
334static inline void destroy_rcu_head(struct rcu_head *head)
335{
336}
337
364static inline void init_rcu_head_on_stack(struct rcu_head *head) 338static inline void init_rcu_head_on_stack(struct rcu_head *head)
365{ 339{
366} 340}